public class book {
	private double basePrice = 0;
	private double vat = 0;
	private double discount = 0;
	private double sellPrice;
 
	public book() {
		setBasePrice(0);
		setVat(0);
		setDiscount(0);
	}
 
	public book(double basePrice, double discount, double vat) {
		setBasePrice(basePrice);
		setVat(discount);
		setDiscount(vat);
	}
 
	public double getBasePrice() {
		return basePrice;
	}
 
	public void setBasePrice(double basePrice) {
		if (basePrice >= 0)
			this.basePrice = basePrice;
		setSellPrice();
	}
 
	public double getVat() {
		return vat;
	}
 
	public void setVat(double vat) {
		if (vat >= 0)
			this.vat = vat;
		setSellPrice();
	}
 
	public double getDiscount() {
		return discount;
	}
 
	public void setDiscount(double discount) {
		if (discount >= 0)
			this.discount = discount;
		setSellPrice();
	}
 
	public double getSellPrice() {
		return sellPrice;
	}
 
	private void setSellPrice() {
		sellPrice = basePrice * ((100 + (vat - discount)) / 100);
	}
 
}

package com.bookPortal.model;
 
public class Book {
	private double basePrice = 0;
	private int vat = 0;
	private int discount = 0;
	private double sellPrice;
 
	public Book() {
		setBasePrice(0);
		setVat(0);
		setDiscount(0);
	}
 
	public Book(double basePrice, int discount, int vat) {
		setBasePrice(basePrice);
		setVat(discount);
		setDiscount(vat);
	}
 
	public double getBasePrice() {
		return basePrice;
	}
 
	public void setBasePrice(double basePrice) {
		if (basePrice >= 0)
			this.basePrice = basePrice;
		setSellPrice();
	}
 
	public int getVat() {
		return vat;
	}
 
	public void setVat(int vat) {
		if (vat >= 0)
			this.vat = vat;
		setSellPrice();
	}
 
	public int getDiscount() {
		return discount;
	}
 
	public void setDiscount(int discount) {
		if (discount >= 0)
			this.discount = discount;
		setSellPrice();
	}
 
	public double getSellPrice() {
		return sellPrice;
	}
 
	private void setSellPrice() {
		sellPrice = basePrice * (100 + vat - discount) / 100;
		if (sellPrice < 0)
			sellPrice = 0;
	}
 
}

package com.bookPortal.modelTest;
 
import com.bookPortal.model.Book;
 
import junit.framework.TestCase;
 
public class BookTest extends TestCase{
	Book b = new Book();
 
	public void testSetBasePrice(){
		b.setBasePrice(10);
		assertEquals(10.0, b.getBasePrice());
	}
	public void testWrongSetBasePrice(){
		b.setBasePrice(-10);
		assertEquals(0.0, b.getBasePrice());
	}
 
	public void testSetVat(){
		b.setVat(10);
		assertEquals(10, b.getVat());
	}
	public void testWrongSetVat(){
		b.setVat(-10);
		assertEquals(0, b.getVat());
	}
 
	public void testSetDiscount(){
		b.setDiscount(10);
		assertEquals(10, b.getDiscount());
	}
	public void testWrongSetDiscount(){
		b.setDiscount(-10);
		assertEquals(0, b.getDiscount());
	}
 
	public void testSetSellPrice(){
		b.setBasePrice(10);
		b.setDiscount(0);
		b.setVat(18);
		assertEquals(11.80, b.getSellPrice());
	}
	public void testWrongSetSellPrice(){
		b.setBasePrice(0);
		b.setDiscount(50);
		b.setVat(18);
		assertEquals(0.0, b.getSellPrice());
	}
 
}